1. Field of the Invention
The present invention relates to a discharge lamp lighting circuit which uses a capacitor to control the supply of transient power to obtain a satisfactory starting performance for a discharge lamp.
2. Description of the Related Art
A related art discharge lamp lighting circuit configuration includes a direct-current power source circuit, a DC-AC converter and a starting circuit (i.e., a starter). With this related art configuration, the discharge lamp lighting circuit (while in a steady state) supplies a rated power to a discharge lamp.
To quickly raise the luminous flux of the discharge lamp, during a transition period immediately following the lighting of the discharge lamp, power exceeding the rated power is supplied to the discharge lamp to accelerate the emission of light (see JP-A-9-330795, for example).
For a related art circuit for lighting a discharge lamp containing mercury, for example, during a transition period extending from immediately following the lighting of the discharge lamp until it is shifted to the steady state, a lamp current (or power to be supplied) corresponding to a lamp voltage is regulated, i.e., a control process is performed based on a so-called control line.
For a lighting circuit for a discharge lamp that contains either no mercury or only a small amount of mercury, starting performance variances constitute a problem when the control method employed uses a control line as a reference. Therefore, predictive control is required for the change in power.
However, with the related art configuration, there are various inconveniences associated with the control arrangement for reducing the starting time for a discharge lamp.
For example but not by way of limitation, costs rise because either the structure of a circuit is complicated or the scale of the circuit is increased. Further, there is a design problem (e.g., that there is nothing in common with the circuit structure for a discharge lamp that contains mercury and the circuit structure for a discharge lamp that contains no mercury or only a small amount of mercury) and the multiplicity of the use of the circuit is poor.